Radiographic examination is often inadequate for an exact evaluation of the state of union of a healing fracture and to detect early stages of osteoporosis. Therefore, there is a definite need for additional non-invasive means to measure the rate of fracture healing and to determine the mechanical integrity of bone in-vivo. Ultrasonic and vibration tests have been attempted before as diagnostic tools to determine the degree of union of healing fractures. However, soft tissue related effects make such tests less reliable and therefore clinically less useful. We have developed a non-contacting electromagnetic device which can detect the propagation of stress-waves in a bone (produced by piezoelectric transducers or by a small impact) in a manner independent of the mechanical properties of the soft tissue. This device monitors the magnetic field produced by the piezoelectric charge associated with a stress wave propagating along a long bone. We have also monitored the stress-waves in bone by a vibrating traction pin placed in a magnetic field. Both of these methods have been used to record stress-waves proximal and distal to the site of a partial fracture in excised human long bones. Significant correlations between the transmission coefficients of the wave and the degree of simulated fracture healing and microstructural variables such as porosity of the bone, have been found. We propose to conduct fracture healing experiments on dogs so that characteristics of the transmitted wave pulse could be calibrated to indicate the state of the healing as evaluated by clinical observation, histological and x-ray examination, and mechanical testing. The sensitivity of the electromagnetic detector will also be improved so that it could be used easily to monitor the rate of fracture healing in patients. It is expected that development of such a method will result in improved health care of patients with fractured bones or other bone lesions. Such a method would also make it possible to detect osteoporosis at an early stage.